Device for crucible-free or floating-zone melting a crystalline rod, especially a semiconductor rod

ABSTRACT

Device for floating-zone melting a crystalline rod includes a flat-wound induction heating coil adapted to encircle a crystalline rod so as to maintain a molten zone therein, and a slotted hollow member of electrically conductive material disposed coaxially to the flat-wound coil in close coupling therewith, the hollow member having an axial length many times greater than that of the flat-wound coil.



1. In a device for floating-zone melting a crystalline rod, a flat-wound induction heating coil adapted to encircle a crystalline rod so as to maintain a molten zone therein, and a slotted hollow member of electrically conductive material disposed coaxially to said flat-wound coil, said flat-wound coil having an outer edge directly connected to said hollow member, said hollow member having an axial length considerably greater than that of said flat-wound coil.
 2. Device according to claim 1 wherein said flat-wound coil is located substantially at the axial center of said hollow member.
 3. Device according to claim 1 wherein said hollow member has a substantially cylindrical shape.
 4. Device according to claim 1 wherein said hollow member is frustoconical and flares outwardly from said flat-wound coil in the axial direction thereof.
 5. In a device for floating-zone melting a crystalline rod, a flat-wound induction heating coil adapted to encircle a crystalline rod so as to maintain a molten zone therein, and a slotted hollow member of electrically conductive material disposed coaxially to said flat-wound coil in close coupling therewith, said hollow member having an axial length considerably greater than that of said flat-wound coil and comprising a pair of frustoconical portions respectively flaring outwardly from opposite sides of said flat-wound coil.
 6. Device according to claim 1 wherein said heating coil is formed with a single flat winding having a width in the radial direction of said coil that is greater than the thicknesses of said winding at the inner and outer peripheries thereof.
 7. In a device for floating-zone melting a crystalline rod, a flat-wound induction heating coil adapted to encircle a crystalline rod so as to maintain a molten zone therein, and a slotted hollow member of electrically conductive material disposed coaxially to said flat-wound coil in close coupling therewith, said hollow member having an axial length considerably greater than that of said flat-wound coil, said heating coil being formed with a single flat winding having a width in the radial direction of said coil that is greater than the thicknesses of said winding at the inner and outer peripheries thereof, the thickness of said winding at said outer periphery thereof being greater than at said inner periphery thereof.
 8. In a device for floating-zone melting a crystalline rod, a flat-wound induction heating coil adapted to encircle a crystalline rod so as to maintain a molten zone therein, and a slotted hollow member of electrically conductive material disposed coaxially to said flat-wound coil in close coupling therewith, said hollow member having an axial length considerably greater than that of said flat-wound coil, said flat-wound coil and said hollow member forming an integral double-walled structure having a hollow space between the respective double walls thereof, and including circulating means communicating with said hollow space for circulating cooling medium therethrough.
 9. Device according to claim 1 wherein the flat-wound coil and the hollow member are formed of an electrically conductive metal selected from the group consisting of copper and silver. 